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Re: Basic misunderstanding on object creation

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From Ian Kelly <ian.g.kelly@gmail.com>
Date Wed, 13 May 2015 08:54:28 -0600
Subject Re: Basic misunderstanding on object creation
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On Wed, May 13, 2015 at 8:42 AM, andrew cooke <andrew@acooke.org> wrote:
> On Wednesday, 13 May 2015 11:36:12 UTC-3, Thomas Rachel  wrote:
>> Am 13.05.2015 um 15:25 schrieb andrew cooke:
>>
>> >>>> class Foo:
>> > ...     def __new__(cls, *args, **kargs):
>> > ...         print('new', args, kargs)
>> > ...         super().__new__(cls, *args, **kargs)
>>
>> > new (1,) {}
>> > Traceback (most recent call last):
>> >    File "<stdin>", line 1, in <module>
>> >    File "<stdin>", line 4, in __new__
>> > TypeError: object() takes no parameters
>>
>> object's __new__() dosn't take any parameters. So call it without arguments:
>>
>> class Foo:
>>      def __new__(cls, *args, **kargs):
>>          print('new', args, kargs)
>>          super().__new__(cls)
>>
>> (at least if we know that we inherit from object. Might be that this one
>> doesn't work very good with multiple inheritance...)
>>
>>
>> Thomas
>
> But then nothing will be passed to __init__ on the subclass.

__init__ is not called by __new__. In the object construction, __new__
is called, and *then* __init__ is called on the result.

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Thread

Basic misunderstanding on object creation andrew cooke <andrew@acooke.org> - 2015-05-13 06:25 -0700
  Re: Basic misunderstanding on object creation Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2015-05-13 16:24 +0200
    Re: Basic misunderstanding on object creation andrew cooke <andrew@acooke.org> - 2015-05-13 07:42 -0700
      Re: Basic misunderstanding on object creation andrew cooke <andrew@acooke.org> - 2015-05-13 07:45 -0700
        Re: Basic misunderstanding on object creation Peter Otten <__peter__@web.de> - 2015-05-13 16:55 +0200
        Re: Basic misunderstanding on object creation Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-13 08:55 -0600
          Re: Basic misunderstanding on object creation andrew cooke <andrew@acooke.org> - 2015-05-13 08:52 -0700
      Re: Basic misunderstanding on object creation Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-13 08:54 -0600
  Re: Basic misunderstanding on object creation Terry Reedy <tjreedy@udel.edu> - 2015-05-13 12:36 -0400
    Re: Basic misunderstanding on object creation andrew cooke <andrew@acooke.org> - 2015-05-13 11:42 -0700
      Re: Basic misunderstanding on object creation Terry Reedy <tjreedy@udel.edu> - 2015-05-13 15:17 -0400
      Re: Basic misunderstanding on object creation Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-13 20:45 +0100
        Re: Basic misunderstanding on object creation Ned Batchelder <ned@nedbatchelder.com> - 2015-05-13 13:33 -0700
          Re: Basic misunderstanding on object creation Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-14 11:07 +1000
  Re: Basic misunderstanding on object creation Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-13 17:38 +0100
  Re: Basic misunderstanding on object creation Terry Reedy <tjreedy@udel.edu> - 2015-05-13 13:05 -0400
  Re: Basic misunderstanding on object creation Terry Reedy <tjreedy@udel.edu> - 2015-05-13 13:13 -0400
  Re: Basic misunderstanding on object creation Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-13 18:43 +0100

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